343 lines
8.4 KiB
C
343 lines
8.4 KiB
C
/*
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* Copyright (c) 2005 David Xu <davidxu@freebsd.org>
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* Copyright (C) 2003 Daniel M. Eischen <deischen@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/types.h>
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#include <sys/queue.h>
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#include <stdlib.h>
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#include <string.h>
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#include <pthread.h>
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#include "thr_private.h"
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#include "libc_private.h"
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/*#define DEBUG_THREAD_LIST */
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#ifdef DEBUG_THREAD_LIST
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#define DBG_MSG stdout_debug
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#else
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#define DBG_MSG(x...)
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#endif
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#define MAX_THREADS 100000
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/*
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* Define a high water mark for the maximum number of threads that
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* will be cached. Once this level is reached, any extra threads
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* will be free()'d.
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*/
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#define MAX_CACHED_THREADS 100
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/*
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* We've got to keep track of everything that is allocated, not only
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* to have a speedy free list, but also so they can be deallocated
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* after a fork().
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*/
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static TAILQ_HEAD(, pthread) free_threadq;
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static umtx_t free_thread_lock;
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static umtx_t tcb_lock;
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static int free_thread_count = 0;
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static int inited = 0;
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static int total_threads;
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LIST_HEAD(thread_hash_head, pthread);
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#define HASH_QUEUES 128
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static struct thread_hash_head thr_hashtable[HASH_QUEUES];
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#define THREAD_HASH(thrd) (((unsigned long)thrd >> 8) % HASH_QUEUES)
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static void thr_destroy(struct pthread *curthread, struct pthread *thread);
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void
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_thr_list_init(void)
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{
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int i;
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_gc_count = 0;
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total_threads = 1;
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_thr_umtx_init(&_thr_list_lock);
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TAILQ_INIT(&_thread_list);
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TAILQ_INIT(&free_threadq);
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_thr_umtx_init(&free_thread_lock);
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_thr_umtx_init(&tcb_lock);
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if (inited) {
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for (i = 0; i < HASH_QUEUES; ++i)
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LIST_INIT(&thr_hashtable[i]);
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}
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inited = 1;
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}
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void
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_thr_gc(struct pthread *curthread)
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{
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struct pthread *td, *td_next;
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TAILQ_HEAD(, pthread) worklist;
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TAILQ_INIT(&worklist);
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THREAD_LIST_LOCK(curthread);
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/* Check the threads waiting for GC. */
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for (td = TAILQ_FIRST(&_thread_gc_list); td != NULL; td = td_next) {
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td_next = TAILQ_NEXT(td, gcle);
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if (td->tid != TID_TERMINATED) {
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/* make sure we are not still in userland */
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continue;
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}
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_thr_stack_free(&td->attr);
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if (((td->tlflags & TLFLAGS_DETACHED) != 0) &&
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(td->refcount == 0)) {
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THR_GCLIST_REMOVE(td);
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/*
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* The thread has detached and is no longer
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* referenced. It is safe to remove all
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* remnants of the thread.
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*/
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THR_LIST_REMOVE(td);
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TAILQ_INSERT_HEAD(&worklist, td, gcle);
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}
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}
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THREAD_LIST_UNLOCK(curthread);
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while ((td = TAILQ_FIRST(&worklist)) != NULL) {
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TAILQ_REMOVE(&worklist, td, gcle);
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/*
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* XXX we don't free initial thread, because there might
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* have some code referencing initial thread.
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*/
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if (td == _thr_initial) {
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DBG_MSG("Initial thread won't be freed\n");
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continue;
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}
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_thr_free(curthread, td);
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}
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}
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struct pthread *
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_thr_alloc(struct pthread *curthread)
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{
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struct pthread *thread = NULL;
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struct tcb *tcb;
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if (curthread != NULL) {
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if (GC_NEEDED())
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_thr_gc(curthread);
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if (free_thread_count > 0) {
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THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
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if ((thread = TAILQ_FIRST(&free_threadq)) != NULL) {
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TAILQ_REMOVE(&free_threadq, thread, tle);
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free_thread_count--;
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}
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THR_LOCK_RELEASE(curthread, &free_thread_lock);
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}
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}
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if (thread == NULL) {
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if (total_threads > MAX_THREADS)
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return (NULL);
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atomic_fetchadd_int(&total_threads, 1);
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thread = malloc(sizeof(struct pthread));
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if (thread == NULL) {
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atomic_fetchadd_int(&total_threads, -1);
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return (NULL);
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}
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}
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if (curthread != NULL) {
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THR_LOCK_ACQUIRE(curthread, &tcb_lock);
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tcb = _tcb_ctor(thread, 0 /* not initial tls */);
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THR_LOCK_RELEASE(curthread, &tcb_lock);
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} else {
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tcb = _tcb_ctor(thread, 1 /* initial tls */);
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}
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if (tcb != NULL) {
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memset(thread, 0, sizeof(*thread));
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thread->tcb = tcb;
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} else {
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thr_destroy(curthread, thread);
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atomic_fetchadd_int(&total_threads, -1);
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thread = NULL;
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}
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return (thread);
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}
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void
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_thr_free(struct pthread *curthread, struct pthread *thread)
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{
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DBG_MSG("Freeing thread %p\n", thread);
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/*
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* Always free tcb, as we only know it is part of RTLD TLS
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* block, but don't know its detail and can not assume how
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* it works, so better to avoid caching it here.
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*/
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if (curthread != NULL) {
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THR_LOCK_ACQUIRE(curthread, &tcb_lock);
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_tcb_dtor(thread->tcb);
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THR_LOCK_RELEASE(curthread, &tcb_lock);
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} else {
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_tcb_dtor(thread->tcb);
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}
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thread->tcb = NULL;
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if ((curthread == NULL) || (free_thread_count >= MAX_CACHED_THREADS)) {
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thr_destroy(curthread, thread);
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atomic_fetchadd_int(&total_threads, -1);
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} else {
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/*
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* Add the thread to the free thread list, this also avoids
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* pthread id is reused too quickly, may help some buggy apps.
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*/
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THR_LOCK_ACQUIRE(curthread, &free_thread_lock);
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TAILQ_INSERT_TAIL(&free_threadq, thread, tle);
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free_thread_count++;
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THR_LOCK_RELEASE(curthread, &free_thread_lock);
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}
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}
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static void
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thr_destroy(struct pthread *curthread __unused, struct pthread *thread)
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{
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free(thread);
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}
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/*
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* Add the thread to the list of all threads and increment
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* number of active threads.
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*/
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void
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_thr_link(struct pthread *curthread, struct pthread *thread)
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{
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THREAD_LIST_LOCK(curthread);
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THR_LIST_ADD(thread);
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_thread_active_threads++;
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THREAD_LIST_UNLOCK(curthread);
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}
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/*
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* Remove an active thread.
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*/
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void
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_thr_unlink(struct pthread *curthread, struct pthread *thread)
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{
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THREAD_LIST_LOCK(curthread);
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THR_LIST_REMOVE(thread);
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_thread_active_threads--;
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THREAD_LIST_UNLOCK(curthread);
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}
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void
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_thr_hash_add(struct pthread *thread)
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{
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struct thread_hash_head *head;
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head = &thr_hashtable[THREAD_HASH(thread)];
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LIST_INSERT_HEAD(head, thread, hle);
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}
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void
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_thr_hash_remove(struct pthread *thread)
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{
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LIST_REMOVE(thread, hle);
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}
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struct pthread *
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_thr_hash_find(struct pthread *thread)
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{
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struct pthread *td;
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struct thread_hash_head *head;
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head = &thr_hashtable[THREAD_HASH(thread)];
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LIST_FOREACH(td, head, hle) {
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if (td == thread)
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return (thread);
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}
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return (NULL);
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}
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/*
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* Find a thread in the linked list of active threads and add a reference
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* to it. Threads with positive reference counts will not be deallocated
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* until all references are released.
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*/
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int
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_thr_ref_add(struct pthread *curthread, struct pthread *thread,
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int include_dead)
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{
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int ret;
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if (thread == NULL)
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/* Invalid thread: */
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return (EINVAL);
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THREAD_LIST_LOCK(curthread);
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if ((ret = _thr_find_thread(curthread, thread, include_dead)) == 0) {
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thread->refcount++;
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}
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THREAD_LIST_UNLOCK(curthread);
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/* Return zero if the thread exists: */
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return (ret);
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}
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void
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_thr_ref_delete(struct pthread *curthread, struct pthread *thread)
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{
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THREAD_LIST_LOCK(curthread);
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_thr_ref_delete_unlocked(curthread, thread);
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THREAD_LIST_UNLOCK(curthread);
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}
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void
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_thr_ref_delete_unlocked(struct pthread *curthread, struct pthread *thread)
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{
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if (thread != NULL) {
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thread->refcount--;
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if ((thread->refcount == 0) && thread->state == PS_DEAD &&
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(thread->tlflags & TLFLAGS_DETACHED) != 0)
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THR_GCLIST_ADD(thread);
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}
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}
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int
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_thr_find_thread(struct pthread *curthread, struct pthread *thread,
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int include_dead)
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{
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struct pthread *pthread;
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if (thread == NULL)
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/* Invalid thread: */
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return (EINVAL);
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pthread = _thr_hash_find(thread);
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if (pthread) {
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if (include_dead == 0 && pthread->state == PS_DEAD) {
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pthread = NULL;
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}
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}
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/* Return zero if the thread exists: */
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return ((pthread != NULL) ? 0 : ESRCH);
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}
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